In downhole ranging applications which use electromagnetic (“EM”) signals traveling along a pipe, estimation of signal strength at different positions along the pipe is critical. The signal may vary due to different formation properties, different well casing size and configuration, etc., such that the sensors may not be able to accurately determine the location of the downhole source. Therefore, in well drilling and logging system design, it is desirable to have an estimation of system performance.
In EM telemetry system design, it is important to have an idea of the estimated signal level that can be received at the surface based on the tool and environmental parameters. Excitation energy provided from the excitation source can then be chosen from the estimation. Transmitter, receiver, and repeaters can also be designed and positioned based on the estimation. In magnetic ranging system design using a surface excitation source, it is important to make sure there is sufficient current flow along the target well necessary to generate enough signal for sensors in the drilling well to detect. Hence, an estimation of the current distribution along drilling tool is important for designers to predict the feasibility of the system and thereby select the input power for the excitation source.